Added npm-shrinkwrap.json to lock down package versions

Also overrides version of bower for grunt-bower-task,
because all bowers <1.3.8 became buggy.
See https://github.com/bower/bower/pull/1403

Change-Id: I24fb24967b4870b5c6291b3f48451ef69e0bbe44
Closes-Bug: 1341156